Multiple layer stent

Abstract

A radially self-expanding stent having multiple layers includes a medial region and proximal and distal cuffs having diameters greater than the medial region diameter when the stent is in the relaxed state. A silicone coating circumscribes at least the medial region of the stent. A deployment device for the stent includes an inner tube surrounded by the stent along with an outer tube that radially compresses the stent. A low durometer sleeve, fixed to the inner tube and in surface engagement with the compressed stent, tends to fix the axial position of the stent relative to the inner tube whenever the outer tube is moved axially relative to the inner tube. Consequently, precision in stent placement and the ability to recapture a partially deployed stent are enhanced.

The invention claimed is: 
     
       1. A stent comprising: a first layer of material defining a generally hollow, tubular construction;   a second layer of material comprising a plurality of thread elements helically wound around a longitudinal axis to provide a self-expanding braided mesh construction and defining a generally hollow, tubular construction disposed inside of the first layer of material; and   a layer of polymeric material disposed between the first layer of material and the second layer of material.   
     
     
       2. The stent of claim 1 wherein the first layer of material comprises a plurality of thread elements helically wound around a longitudinal axis to provide a self-expanding braided mesh construction. 
     
     
       3. The stent of claim 1 wherein at least one of the first layer of material or the second layer of material has a proximal portion, a distal portion and a medial portion located between the proximal portion and the distal portion and wherein at least one of the proximal portion or the distal portion has a diameter larger than the diameter of the medial portion when the stent is in an unconstrained condition. 
     
     
       4. The stent of claim 2 wherein at least one of the first layer of material or the second layer of material has a proximal portion, a distal portion and a medial portion located between the proximal portion and the distal portion and wherein at least one of the proximal portion or the distal portion has a diameter larger than the diameter of the medial portion when the stent is in an unconstrained condition. 
     
     
       5. The stent of claim 1 wherein the second layer of material has a length greater than the length of the first layer of material. 
     
     
       6. The stent of claim 5 wherein the layer of polymeric material extends only along the length of the first layer of material. 
     
     
       7. The stent of claim 5 wherein at least one of the first layer of material or the second layer of material has a proximal portion, a medial portion and a distal portion and wherein at least one of the proximal portion or the distal portion has a diameter larger than the diameter of the medial portion when the stent is an unconstrained condition. 
     
     
       8. The stent of claim 6 wherein at least one of the first layer of material or the second layer of material has a proximal portion, a medial portion and a distal portion and wherein at least one of the proximal portion or the distal portion has a diameter larger than the diameter of the medial portion when the stent is an unconstrained condition. 
     
     
       9. A multiple layer stent comprising: an outer generally hollow tubular stent formed from at least one thread element helically wound around a longitudinal axis of the multiple layer stent to provide a braided mesh construction;   an inner generally hollow tubular self-expanding stent coaxially disposed within the outer stent and formed from at least one thread element helically wound around a longitudinal axis of the multiple layer stent to provide a braided mesh construction; and   a layer of polymeric material covering at least a portion of the multiple layer stent.   
     
     
       10. The multiple layer stent of claim 9 wherein the inner stent has an axial length greater than the axial length of the outer stent. 
     
     
       11. The multiple layer stent of claim 10 wherein the layer of polymeric material extends along at least the length of the outer stent. 
     
     
       12. The multiple layer stent of claim 9 wherein the inner stent and outer stent both have a proximal portion, a medial portion and a distal portion wherein at least one of the proximal portion or the distal portion of both the inner stent and the outer stent have a diameter larger than the diameter of the medial portion when the multiple layer stent is in an unconstrained condition. 
     
     
       13. The multiple layer stent of claim 10 wherein the inner stent and outer stent both have a proximal portion, a medial portion and a distal portion wherein at least one of the proximal portion or the distal portion of both the inner stent and the outer stent have a diameter larger than the diameter of the medial portion when the multiple layer stent is in an unconstrained condition. 
     
     
       14. The multiple layer stent of claim 11 wherein the inner stent and outer stent both have a proximal portion, a medial portion and a distal portion wherein at least one of the proximal portion or the distal portion of both the inner stent and the outer stent have a diameter larger than the diameter of the medial portion when the multiple layer stent is in an unconstrained condition. 
     
     
       15. A stent comprising: a first layer of material having an axial length and defining a generally hollow, tubular construction;   a second layer of material having an axial length greater than the axial length of the first layer and defining a generally hollow, tubular construction disposed inside of the first layer of material; and   a layer of polymeric material disposed between the first layer of material and the second layer of material.   
     
     
       16. The stent of claim 15 wherein at least one of the first layer of material or the second layer of material is a plurality of thread elements helically wound around a longitudinal axis of the first layer of material to provide a braided mesh construction. 
     
     
       17. The stent of claim 15 wherein the layer of polymeric material extends only along the length of the first layer of material. 
     
     
       18. The stent of claim 15 wherein at least one of the first layer of material or the second layer of material has a proximal portion, a medial portion and a distal portion and wherein at least one of the proximal portion or the distal portion has a diameter larger than the diameter of the medial portion when the stent is an unconstrained condition. 
     
     
       19. The stent of claim 17 wherein at least one of the first layer of material or the second layer of material has a proximal portion, a medial portion and a distal portion and wherein at least one of the proximal portion or the distal portion has a diameter larger than the diameter of the medial portion when the stent is an unconstrained condition. 
     
     
       20. A multiple layer stent comprising: an outer generally hollow tubular stent having an axial length formed from at least one thread element helically wound around a longitudinal axis of the multiple layer stent to provide a braided mesh construction;   an inner generally hollow tubular stent greater than the axial length of the outer stent and coaxially disposed within the outer stent and formed from at least one thread element helically wound around a longitudinal axis of the multiple layer stent to provide a braided mesh construction; and   a layer of polymeric material covering at least a portion of the multiple layer stent.   
     
     
       21. The multiple layer stent of claim 20 wherein the layer of polymeric material extends along at least the length of the outer stent. 
     
     
       22. The multiple layer stent of claim 20 wherein the inner stent and outer stent both have a proximal portion, a medial portion and a distal portion wherein at least one of the proximal portion or the distal portion of both the inner stent and the outer stent have a diameter larger than the diameter of the medial portion when the multiple layer stent is in an unconstrained condition.